<!--
	名称:css-子div设置margin-top后，父div与子div一起下移
	实现:在父级添加border或者padding（16行或者17行）
	来源:https://www.baidu.com/link?url=C76cXODaeQfWQSYHHsEuA5D8_N5IYYPjis0ojHXQt4ZQZ_8vM3Q8Y9VwTcyIEgElYOWINS6mwyUAFgJs-5ZZlq&wd=&eqid=c281b4490000c73d000000065a470b18
-->
<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
    .father{
        width:200px;
        height:200px;
        background:red;
        /*border-top: 1px solid #0f0;*/
       /*padding-top: 1px;*/
    }
    .son{
        background:purple;
        margin-top:50px;
    }
</style>
	</head>
	<body>
		<div class="father">
        <div class="son">123</div>
    </div>
	</body>
</html>
